a9e659619f
Summary: Adapt implementation of Library Fundamentals TS optional into an implementation of N4606 optional. - Update relational operators per http://wg21.link/P0307 - Update to requirements of http://wg21.link/P0032 - Extension: Implement trivial copy/move construction/assignment for `optional<T>` when `T` is trivially copyable. Audit P/Rs for optional LWG issues: - 2756 "C++ WP optional<T> should 'forward' T's implicit conversions" Implemented, which also resolves 2753 "Optional's constructors and assignments need constraints" (modulo my refusal to explicitly delete the move operations, which is a design error that I'm working on correcting in the 2756 P/R). - 2736 "nullopt_t insufficiently constrained" Already conforming. I've added a test ensuring that `nullopt_t` is not copy-initializable from an empty braced-init-list, which I believe is the root intent of the issue, to avoid regression. - 2740 "constexpr optional<T>::operator->" Already conforming. - 2746 "Inconsistency between requirements for emplace between optional and variant" No P/R, but note that the author's '"suggested resolution" is already implemented. - 2748 "swappable traits for optionals" Already conforming. - 2753 "Optional's constructors and assignments need constraints" Implemented. Most of the work for this patch was done by Casey Carter @ Microsoft. Thank you Casey! Reviewers: mclow.lists, CaseyCarter, EricWF Differential Revision: https://reviews.llvm.org/D22741 llvm-svn: 283980
46 lines
1.1 KiB
C++
46 lines
1.1 KiB
C++
//===----------------------------------------------------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is dual licensed under the MIT and the University of Illinois Open
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// Source Licenses. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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// UNSUPPORTED: c++98, c++03, c++11, c++14
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// <optional>
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// template <class T, class... Args>
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// constexpr optional<T> make_optional(Args&&... args);
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#include <optional>
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#include <string>
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#include <memory>
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#include <cassert>
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int main()
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{
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using std::optional;
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using std::make_optional;
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{
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constexpr auto opt = make_optional<int>('a');
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static_assert(*opt == int('a'), "");
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}
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{
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std::string s("123");
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auto opt = make_optional<std::string>(s);
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assert(*opt == s);
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}
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{
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std::unique_ptr<int> s(new int(3));
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auto opt = make_optional<std::unique_ptr<int>>(std::move(s));
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assert(**opt == 3);
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assert(s == nullptr);
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}
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{
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auto opt = make_optional<std::string>(4, 'X');
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assert(*opt == "XXXX");
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}
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}
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